8th Grade Scatter Plots and Association Test with Point Values (PDF)
This grade 8 scatter plots test for 8th Grade covers scatter plots and association (Common Core 8.SP.A.1, 8.SP.A.2), with a free PDF to print.
This 20-point test checks scatter plots, patterns of association, outliers and informal trend lines (Common Core 8.SP.A.1 and 8.SP.A.2). Work alone, show every step, and write each final answer clearly. You have 45 minutes. Calculators are not needed unless a question says so.
Time and points
- Grade: Grade 8
- Chapter: Scatter Plots and Association
- Standards: 8.SP.A.1, 8.SP.A.2
- Time: 45 minutes
- Total: 20 points
Grade 8 scatter plots test: questions
Question 1 – Describe the pattern [3 pts]
Describe the association between the variables: type (positive, negative or none), shape (linear or nonlinear), and strength.
Question 2 – Identify an outlier [2 pts]
Identify the outlier and say how it differs from the other points.
Question 3 – Predict the association [2 pts]
For each pair, predict the association: (a) a car’s speed and the time to travel 100 miles, (b) a person’s age and the number of letters in their first name.
Question 4 – Slope of a trend line [3 pts]
A trend line passes through \((65, 25)\) and \((95, 61)\). Find its slope and explain what it means for the ice cream truck.
Question 5 – Use a trend line [3 pts]
The trend line \(y = 5.3x + 47\) models the score \(y\) after \(x\) hours of study. Predict the score for 5 hours. Is it reasonable to use this line for 20 hours? Explain.
Question 6 – Compare lines [3 pts]
The plot shows car value (thousands of dollars) by age with a trend line. Two students draw different lines: \(y = -1.8x + 23.7\) and \(y = -3x + 30\). Which fits better? Use the point at age 8.
Question 7 – Cause [2 pts]
A study finds that cities with more ice cream shops also have more swimming pool accidents. Does one cause the other? Explain.
Question 8 – Draw a conclusion [2 pts]
A scatter plot has points in two clusters with no pattern between the clusters. Describe what the clusters mean.
Key facts behind this grade 8 scatter plots test
- Positive association: as x increases, y tends to increase.
- Negative association: as x increases, y tends to decrease.
- Clusters are groups of points; outliers are points far from the pattern.
- A linear association has points near a straight line; nonlinear follows a curve.
- A trend line has about as many points above as below and is close to the points.
How to use this grade 8 scatter plots test
Time yourself: the test is designed for an average student in 45 minutes. Answer the questions you are sure of first, then come back to the longer ones and check your units.
All Grade 8 chapters: Grade 8 math.
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